<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>01_CSS显示模式</title>
    <style>
        div{
            width: 100px;
            height: 100px;
            border: 5px solid #FF0000;
            /*块级元素: 默认竖着排 且可以设置宽高*/
            display: block;
        }
        span{
            background-color: #FF0;
            display: block;
            width: 100px;
            height: 100px;
        }
        input,button{
            display: inline-block;
            width: 200px;
            height: 200px;
        }
        .d2:hover{
            display: none;
        }

    </style>
</head>
<body>
    <div class="d1"></div>
    <div class="d2"></div>
    <div class="d3"></div>
    <hr>
<span>123456789</span>
<span>123456789</span>
<span>123456789</span>
    <hr>
    <input type="text">
    <input type="text">
    <input type="text">
<button></button>
</body>
</html>